(also known as the Chief Feature by students of G.I. Gurdjieff) See The Revolution of the Dialectic, by Samael Aun Weor, chapters 2-4.
"Awakening is only possible by destroying the “I,” the ego. We have to recognize with complete clarity that each person has his own Particular Characteristic Psychological Feature (PCPF), which we have spoken about many times before. Certainly, each person has his own particular characteristic psychological feature, this is a fact. Some will have lust as their characteristic feature; others will have hatred; for others it will be covetousness, etc. The feature is the sum of several particular characteristic psychological elements. For each PCPF, a definitive event, a precise circumstance, always occurs. What if a man is lustful? There will always be circumstances of lust in his life accompanied by specific problems. These circumstances are always repeated. We need to know our PCPF if we want to move on to a superior level of the Being and eliminate from within ourselves the undesirable elements which constitute our psychological feature." - Samael Aun Weor, The Revolution of the Dialectic